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v/vlib/wasm/encoding.v

453 lines
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V

// Copyright (c) 2023 l-m.dev. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module wasm
import encoding.leb128
import math.bits
fn (mut mod Module) u32(v u32) {
mod.buf << leb128.encode_u32(v)
}
fn (mut mod Module) patch_start() int {
return mod.buf.len
}
fn (mut mod Module) patch_len(pos int) {
len := mod.buf.len - pos
data := leb128.encode_u32(u32(len))
mod.buf.insert(pos, data)
}
fn (mut mod Module) patch_u32(pos int, val u32) {
data := leb128.encode_u32(val)
mod.buf.insert(pos, data)
}
fn (mut mod Module) result_type(results []ValType) {
mod.u32(u32(results.len))
for r in results {
mod.buf << u8(r)
}
}
fn (mut mod Module) function_type(ft FuncType) {
mod.buf << 0x60 // function type indicator
mod.result_type(ft.parameters)
mod.result_type(ft.results)
}
fn (mut mod Module) global_type(vt ValType, is_mut bool) {
mod.buf << u8(vt)
mod.buf << u8(is_mut)
}
fn push_f32(mut buf []u8, v f32) {
rv := bits.f32_bits(v)
buf << u8(rv >> u32(0))
buf << u8(rv >> u32(8))
buf << u8(rv >> u32(16))
buf << u8(rv >> u32(24))
}
fn push_f64(mut buf []u8, v f64) {
rv := bits.f64_bits(v)
buf << u8(rv >> u32(0))
buf << u8(rv >> u32(8))
buf << u8(rv >> u32(16))
buf << u8(rv >> u32(24))
buf << u8(rv >> u32(32))
buf << u8(rv >> u32(40))
buf << u8(rv >> u32(48))
buf << u8(rv >> u32(56))
}
fn (mod &Module) get_function_idx(patch CallPatch) int {
mut idx := -1
match patch {
FunctionCallPatch {
ftt := mod.functions[patch.name] or {
panic('called function ${patch.name} does not exist')
}
idx = ftt.idx + mod.fn_imports.len
}
ImportCallPatch {
for fnidx, c in mod.fn_imports {
if c.mod == patch.mod && c.name == patch.name {
idx = fnidx
break
}
}
if idx == -1 {
panic('called imported function ${patch.mod}.${patch.name} does not exist')
}
}
}
return idx
}
fn (mut mod Module) patch(ft Function) {
mut ptr := 0
for patch in ft.patches {
mut idx := 0
match patch {
CallPatch {
idx = mod.get_function_idx(patch)
}
FunctionGlobalPatch {
idx = mod.global_imports.len + patch.idx
}
}
mod.buf << ft.code[ptr..patch.pos]
mod.u32(u32(idx))
ptr = patch.pos
}
mod.buf << ft.code[ptr..]
}
fn (mut mod Module) name(name string) {
mod.u32(u32(name.len))
mod.buf << name.bytes()
}
fn (mut mod Module) start_subsection(sec Subsection) int {
mod.buf << u8(sec)
return mod.patch_start()
}
fn (mut mod Module) start_section(sec Section) int {
mod.buf << u8(sec)
return mod.patch_start()
}
fn (mut mod Module) end_section(tpatch int) {
mod.patch_len(tpatch)
}
// compile serialises the WebAssembly module into a byte array.
// The returned byte array can be written out into a `.wasm`, or executed in memory.
pub fn (mut mod Module) compile() []u8 {
mod.buf = []u8{cap: 128}
// WASM_BINARY_MAGIC, WASM_BINARY_VERSION
mod.buf << [u8(0x00), 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00]
// https://webassembly.github.io/spec/core/binary/modules.html#type-section
//
if mod.functypes.len > 0 {
tpatch := mod.start_section(.type_section)
{
mod.u32(u32(mod.functypes.len))
for ft in mod.functypes {
mod.function_type(ft)
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#import-section
//
if mod.fn_imports.len > 0 || mod.global_imports.len > 0 {
tpatch := mod.start_section(.import_section)
{
mod.u32(u32(mod.fn_imports.len + mod.global_imports.len))
for ft in mod.fn_imports {
mod.name(ft.mod)
mod.name(ft.name)
mod.buf << 0x00 // function
mod.u32(u32(ft.tidx))
}
for gt in mod.global_imports {
mod.name(gt.mod)
mod.name(gt.name)
mod.buf << 0x03 // global
mod.global_type(gt.typ, gt.is_mut)
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#binary-funcsec
//
if mod.functions.len > 0 {
tpatch := mod.start_section(.function_section)
{
mod.u32(u32(mod.functions.len))
for _, ft in mod.functions {
mod.u32(u32(ft.tidx))
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#binary-memsec
//
if memory := mod.memory {
tpatch := mod.start_section(.memory_section)
{
mod.u32(1)
if max := memory.max {
mod.buf << 0x01 // limit, max present
mod.u32(memory.min)
mod.u32(max)
} else {
mod.buf << 0x00 // limit, max not present
mod.u32(memory.min)
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#global-section
//
if mod.globals.len > 0 {
tpatch := mod.start_section(.global_section)
{
mod.u32(u32(mod.globals.len))
for gt in mod.globals {
mod.global_type(gt.typ, gt.is_mut)
{
mut ptr := 0
for patch in gt.init.call_patches {
idx := mod.get_function_idx(patch)
mod.buf << gt.init.code[ptr..patch.pos]
mod.u32(u32(idx))
ptr = patch.pos
}
mod.buf << gt.init.code[ptr..]
}
mod.buf << 0x0B // END expression opcode
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#export-section
//
{
tpatch := mod.start_section(.export_section)
{
lpatch := mod.patch_start()
mut lsz := 0
for _, ft in mod.functions {
if !ft.export {
continue
}
lsz++
mod.name(ft.export_name or { ft.name })
mod.buf << 0x00 // function
mod.u32(u32(ft.idx + mod.fn_imports.len))
}
if memory := mod.memory {
if memory.export {
lsz++
mod.name(memory.name)
mod.buf << 0x02 // function
mod.u32(0)
}
}
for idx, gbl in mod.globals {
if !gbl.export {
continue
}
lsz++
mod.name(gbl.name)
mod.buf << 0x03 // global
mod.u32(u32(idx + mod.global_imports.len))
}
mod.patch_u32(lpatch, u32(lsz))
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#binary-startsec
//
if start := mod.start {
ftt := mod.functions[start] or { panic('start function ${start} does not exist') }
tpatch := mod.start_section(.start_section)
{
mod.u32(u32(ftt.idx + mod.fn_imports.len))
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#data-count-section
//
if mod.segments.len > 0 {
tpatch := mod.start_section(.data_count_section)
{
mod.u32(u32(mod.segments.len))
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#binary-codesec
//
if mod.functions.len > 0 {
tpatch := mod.start_section(.code_section)
{
mod.u32(u32(mod.functions.len))
for _, ft in mod.functions {
fpatch := mod.patch_start()
rloc := ft.locals[mod.functypes[ft.tidx].parameters.len..]
{
mod.u32(u32(rloc.len))
for lt in rloc {
mod.u32(1)
mod.buf << u8(lt.typ)
}
mod.patch(ft)
mod.buf << 0x0B // END expression opcode
}
mod.patch_len(fpatch)
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/binary/modules.html#data-section
//
if mod.segments.len > 0 {
tpatch := mod.start_section(.data_section)
{
mod.u32(u32(mod.segments.len))
for _, seg in mod.segments {
if idx := seg.idx {
mod.buf << 0x00 // active
// constant expr
mod.buf << 0x41 // i32.const
mod.buf << leb128.encode_i32(idx)
mod.buf << 0x0B // END expression opcode
} else {
mod.buf << 0x01 // passive
}
mod.u32(u32(seg.data.len))
mod.buf << seg.data
}
}
mod.end_section(tpatch)
}
// https://webassembly.github.io/spec/core/appendix/custom.html#name-section
//
if mod.debug {
tpatch := mod.start_section(.custom_section)
mod.name('name')
if mod_name := mod.mod_name {
mpatch := mod.start_subsection(.name_module)
{
mod.name(mod_name)
}
mod.end_section(mpatch)
}
{
mpatch := mod.start_subsection(.name_function)
{
mod.u32(u32(mod.functions.len + mod.fn_imports.len))
mut idx := 0
for f in mod.fn_imports {
mod.u32(u32(idx))
mod.name('${f.mod}.${f.name}')
idx++
}
for n, _ in mod.functions {
mod.u32(u32(idx))
mod.name(n)
idx++
}
}
mod.end_section(mpatch)
}
{
mpatch := mod.start_subsection(.name_local)
{
fpatch := mod.patch_start()
mut fcount := 0
mut idx := mod.fn_imports.len // after imports
for _, ft in mod.functions {
// only add entry if it contains a local with an assigned name
if ft.locals.any(it.name != none) {
mod.u32(u32(idx)) // function idx
mut lcount := 0
lcpatch := mod.patch_start()
for lidx, loc in ft.locals {
if name := loc.name {
mod.u32(u32(lidx))
mod.name(name)
lcount++
}
}
mod.patch_u32(lcpatch, u32(lcount))
fcount++
}
idx++
}
mod.patch_u32(fpatch, u32(fcount))
}
mod.end_section(mpatch)
}
{
mpatch := mod.start_subsection(.name_type)
{
fpatch := mod.patch_start()
mut fcount := 0
for idx, ft in mod.functypes {
if name := ft.name {
mod.u32(u32(idx))
mod.name(name)
fcount++
}
}
mod.patch_u32(fpatch, u32(fcount))
}
mod.end_section(mpatch)
}
if memory := mod.memory {
mpatch := mod.start_subsection(.name_memory)
{
mod.u32(u32(1)) // one memory in vec
mod.u32(u32(0)) // 0 idx
mod.name(memory.name) // memory name
}
mod.end_section(mpatch)
}
if mod.globals.len != 0 || mod.global_imports.len != 0 {
mpatch := mod.start_subsection(.name_global)
{
fpatch := mod.patch_start()
mut fcount := 0
for gbl in mod.global_imports {
mod.u32(u32(fcount))
mod.name('${gbl.mod}.${gbl.name}')
fcount++
}
for gbl in mod.globals {
mod.u32(u32(fcount))
mod.name(gbl.name)
fcount++
}
mod.patch_u32(fpatch, u32(fcount))
}
mod.end_section(mpatch)
}
if mod.segments.any(it.name != none) {
mpatch := mod.start_subsection(.name_data)
{
fpatch := mod.patch_start()
mut fcount := 0
for idx, ds in mod.segments {
if name := ds.name {
mod.u32(u32(idx))
mod.name(name)
fcount++
}
}
mod.patch_u32(fpatch, u32(fcount))
}
mod.end_section(mpatch)
}
mod.end_section(tpatch)
}
return mod.buf
}